Surface termination modulation for superior S-Scheme Bi₂WO₆/BiOI heterojunction photocatalyst: a hybrid density functional study

Abstract

The prevailing theoretical frameworks indicate that depending on the growth conditions, the Bi2WO6(001) surface can manifest in three distinct terminations—DL-O-Bi (DL: Double layers), O-Bi, and O-W. In this study, we conduct a comprehensive examination of the interplay between these terminations on Bi2WO6(001) and the 1I-terminated BiOI(001) facet, especially focusing on their impact on the photocatalytic activity of Bi2WO6/BiOI heterostructure, applying hybrid functional calculations. The models formulated for this research are designated as Bi2WO6(O-Bi)/BiOI(1I), Bi2WO6(DL-O-Bi)/BiOI(1I), and Bi2WO6(O-W)/BiOI(1I). Our findings reveal that Bi2WO6(O-Bi)/BiOI(1I) shows a type II band alignment, which facilitates the spatial separation of photo-generated electrons and holes. Notably, the Bi2WO6(DL-O-Bi)/BiOI(1I) configuration has the lowest binding energy and results in an S-scheme (or Step-scheme) heterostructure. In contrast to the type II heterostructure, this particular configuration demonstrates enhanced photocatalytic efficiency due to improved photo-generated carrier separation, augmented oxidation capability, and better visible-light absorption. Conversely, Bi2WO6(O-W)/BiOI(1I) presents a type I projected band structure, which is less conducive for the separation of photo-generated electron-hole pairs. In summation, this investigation points out that one could significantly refine the photocatalytic efficacy of not only Bi2WO6/BiOI but also other heterostructure photocatalysts by modulating the coupling of different terminations via precise crystal synthesis or growth conditions.

Strain and Electric Field Engineering of G-ZnO/SnXY (X, Y = S, Se) S-Scheme Heterostructures for Photocatalyst and Electronic Device Applications: A Hybrid DFT Calculation

“…After contact, the electrons transfer from g-ZnO to SnXY due to the E f difference between them, making g-ZnO positively charged, SnXY layers receive electrons and are negatively charged, and E int from g-ZnO to SnXY thus formed. E int in g-ZnO/SnS 2 and g-ZnO/SnSSe are 0.35 and 0.43 V/Å, respectively, larger than that of many reported photocatalytic heterostructures such as V Br -CsSnBr 3 /SnS 2 (0.25 V/Å), RP/CH 3 NH 3 PbI 3 (0.059 V/Å), BiOCl/Bi 2 S 3 -(001) (0.14 V/Å), BiOCl/V S -Bi 2 S 3 -(001) (0.19 V/Å), and Bi 2 WO 6 (DL-O–Bi)/BiOI­(1I) (0.09 V/Å) . When g-ZnO and SnXY are activated by light illumination, photogenerated electrons and holes exist.…”

“…E int in g-ZnO/SnS 2 and g-ZnO/ SnSSe are 0.35 and 0.43 V/Å, respectively, larger than that of many reported photocatalytic heterostructures such as V Br -CsSnBr 3 /SnS 2 (0.25 V/Å), 57 RP/CH 3 NH 3 PbI 3 (0.059 V/ Å), 60 BiOCl/Bi 2 S 3 -(001) (0.14 V/Å), 58 BiOCl/V S -Bi 2 S 3 -(001) (0.19 V/Å), 58 and Bi 2 WO 6 (DL-O−Bi)/BiOI(1I) (0.09 V/ Å). 61 When g-ZnO and SnXY are activated by light illumination, photogenerated electrons and holes exist. Under E int , the recombination of electrons and holes occurs between the VB of g-ZnO and the CB of SnXY.…”